i got a 2001 subaru impreza 2.5...where is the PCV valve and how do i change it...sorry this a noob question...

It is located on the Right side of the Intake Manifold plenum, near the Ignition Coil. It has a rubber hose on it.
Why do you want to change it? There is no maintenance interval for it on Subarus.

It is on the intake manifold and it's pointing diagonally towards the passenger seat. You'll have to use a plier to grab and move the metal lock-ring so you can pull off the hose. You'll then see the PCV valve. IIRC, you'll need to use a monkey wrench to remove it from the intake manifold. Remember to just hand-tight the new one in because the manifold is cast aluminum and you don't want to strip anything.

http://www.ravensblade-impreza.com/modifications/drivetrain/pcv/pcv.html

North covers this on his site.

thanx...to all...especially americanyouth...with them diagrams...